Welcome, rookie. You've had about zero flight experience and we dread to think how well you'll cope, but we're desperate. The Mars defence fleet is sorely lacking pilots and we suddenly have an urgent need for them. We'll hire anyone - Mars is under attack! What started out as a trade embargo has grown much more serious, and the Earth/Mars alliance is now at war with the people of the Asteroid Belt. Can you stop the invaders?

Long-time readers of Bytten may remember an earlier game by Psychic Software - the post-apocalyptic car wars of Darkwind. Do you remember the gritty back story, the violent and often short lives of your gang members, the online gameplay, the range of rather nasty weapons you could employ? Yes? Well, forget all that. This is a very different and more family-friendly game, to the extent that you'd be forgiven for thinking they were written by two completely different developers, and I think this demonstrates the versatility of our independent community. Mars Defender is a much simpler game, based upon the ancient classic, Asteroids.

It's very simple to play. You are given a series of missions, starting out with basic maneouvers and the occasional asteroid heading for Mars, but quickly leading to escorting ships and fending off waves of fighters. Your progress is automatically saved and, if you fail a mission, you can always reattempt it. Having accepted your next task, you pick a ship and off you go. Controls are the classics of Asteroids - left and right turn, forward is thrust and spacebar fires your weapons. Simple! Let's go get those asteroids!

Ah, but it's not as simple as you think. For one thing, you've got a humongous planet in the middle of the play area (usually Mars, though action can also be centred on other locations, such as the Martian moons, Phobos and Diemos). Try not to fly into that, and beware the slight gravitational effect it has, which won't just affect you but also any other ships or rocks in the vicinity. There's an orbiting space station too. During missions you must also ensure that Mars and the station are not destroyed.

The graphics are fairly straightforward, with cartoon pictures for the various characters that interact with you. Ships are 3D rendered and bank as they rotate, though explosions are very simplistic and when a trader ship or similar docks with Mars it simply fades out of existence! I actually struggled with the gameplay at first due to the graphics, as the view zooms in or out relative to your ship's speed. Turn suddenly and thrust the other way, and the screen can rapidly recentre. Hold on to your lunch! Laser blasts are simple lines, much like you'd see in Space Invaders rather than a modern shooter, in different colours depending on what ship is firing them.

The drawback of this system is that you cannot see distant targets unless you go fast, and if you go fast you'll struggle to stop and turn in time. Chasing asteroids is surprisingly difficult at first. Part of the issue is that you can't thrust backwards. If you want to slow down, you have to turn and thrust the other way. This is a little tricky in smaller ships and I found the bigger ones, when unlocked, to be bordering on useless. The Nosferatu, for instance, looks an impressive ship - but it's a big and pretty slow target. Good luck avoiding enemy fighters with that. Bigger ships have more shielding to counter their lack of speed and more powerful guns, which are useful against larger asteroids and tougher foes, but this advantage is no more effective on basic targets, as they all simply fire straight ahead.

Menu and mission briefing screens feature a range of rock tracks, though the main game has some light background noise rather than actual music. This works very well, more so than background music might have done, and allows for fast and slow players alike. If you're struggling to catch an asteroid, a repeating track might become obtrusive after a few minutes. There is of course a suitable range of sound effects, including laser blasts and bangs and thrusters, and these all work well.

At first I struggled with Mars Defender. The screen movement takes some getting used to, and using your thrusters properly takes practice too. It's very easy to overshoot an asteroid or ship and find your shots veering off in strange directions because of the relative velocities involved. I was stuck on level four for a while, in which my enemies are a mere bunch of rocks, simply because I couldn't get close to them without either overshooting or crashing into them. Once I'd got better at flying I found it much easier and shot through the next few levels in fifteen minutes. Bigger ships actually don't have this problem because they are so much slower and more unwieldy, but this also makes them useless in combat against anything small and fast. Like asteroids. Perhaps I need to learn a different way of flying those.

At this stage I'm not really able to say much about the longevity of Mars Defender. Certainly I haven't finished it yet, having got stuck again! You can start a new game at any time and every game is saved, so you can have multiple "profiles" at once. However, there's not much variety. Aside from the new ships, which unlock when you complete set missions, missions are quite similar - blow up the enemies, don't let the civilians die. I've not seen any evidence of a "free play" mode so far and there's no way to replay older missions except by starting a new game. I feel that Mars Defender could do so much more here - what about a classic Asteroids mode, with waves of rocks and no planet, but your choice of starting ship from those unlocked? What about a survival mode, in which waves of asteroids and enemies target Mars and you must hold them off as long as you can? What about more interesting and varied weapons, such as torpedo launchers or beam lasers? The ship AI also needs work. After several collisions with my fellow pilots on mission eight, I've come to the conclusion the safest approach might be to shoot them before you start your patrol before they ram you in combat later on.

Mars Defender is a fun diversion, but it lacks some of the functionality it could easily include with a bit more effort and the playability, while not actually bad, is tricky enough to pick up that it may put off more casual players. I hope that Psychic Software will invest a bit of time in updating these areas - Mars Defender has some character to it; something sorely lacking in all too many titles. This one has promise.